JSR303-仅在填充时验证

Question

I have a field in a Java Bean (kilograms) that is not mandatory, but if the user does enter it, it obviously needs to be a number.

Is there a combination of JSR303 annotations that can enforce that rule? I tried

@Min(value=0)

But that obviously disallows empty, which is allowable.

Thanks for any help.

Answer 1

The documentation says that null values are considered valid. See

http://jackson.codehaus.org/javadoc/bean-validation-api/1.0/javax/validation/constraints/Min.html

You need to use object types (Integer) instead of primitive types. If you have problems with it please show us your bean.

Answer 2

You cannot do a OR composition with Bean Validation 1.0. Hibernate Validator has a feature which allows you do so. It is called "boolean composition of custom constraints" - http://docs.jboss.org/hibernate/stable/validator/reference/en-US/html_single/#d0e3701

So you need a custom constraint and you obviously won't be standard conform, but it works.

For Bean Validation 1.1 there is a discussion whether boolean composition should make it into the standard ( BVAL-260 ), but it is not guaranteed.